Processing an image to sepia tone in Python

Question

I need help figuring out how to convert an image to sepia. This is what I have so far..but it only changes everything to black and white colors with a very small tint of bro

Answer 1

Your gray level image is not a gray level image. In a gray level image all three channels r,g,b have the same value.

Open paint and try it to verify if your code makes sense.

Fix these lines:

newR = (R * 0.393 + G * 0.769 + B * 0.189)
newG = (R * 0.349 + G * 0.686 + B * 0.168)
newB = (R * 0.272 + G * 0.534 + B * 0.131)

Simply use the mean of r,g,b and put it into newR, newG and newG.

There are some weighted means as well. Just Google for RGB to intensity formulas.

Answer 2

You can convert image to sepia by just manipulating the pixel values. The following is the code(Disclaimer : Taken from this article.)

from PIL import Image

def sepia(image_path:str)->Image:
    img = Image.open(image_path)
    width, height = img.size

    pixels = img.load() # create the pixel map

    for py in range(height):
        for px in range(width):
            r, g, b = img.getpixel((px, py))

            tr = int(0.393 * r + 0.769 * g + 0.189 * b)
            tg = int(0.349 * r + 0.686 * g + 0.168 * b)
            tb = int(0.272 * r + 0.534 * g + 0.131 * b)

            if tr > 255:
                tr = 255

            if tg > 255:
                tg = 255

            if tb > 255:
                tb = 255

            pixels[px, py] = (tr,tg,tb)

    return img

Original Image

Sepia Image